Field of the Invention
The present invention relates to a structure for mounting a resolver.
Description of Related Art
As a means for detecting a rotation angle of a motor, a resolver is known. The resolver has a rotor which is fixed to a rotating shaft and is rotated with the rotating shaft, and a stator which is fixed to a housing and is arranged at the outside of the rotor. When the rotor is rotated, the size of an air gap formed between the rotor and the stator changes with the rotation of the rotor. Then, an output corresponding to this change is generated on a detecting coil placed at a stator side, and the rotation angle of the rotor is detected based on this output.
As a structure for fixing a resolver to an object to be mounted, Japanese Unexamined Patent Application Laid-open No. 2013-99000 discloses a structure in which a stator of a resolver is contained in an opening portion of a fixing member and is fixed in a housing by the fixing member. In addition, as a structure for fixing a stator of a resolver to a housing, Japanese Unexamined Patent Application Laid-open No. 2006-242758 discloses a structure in which a protruded flange portion is formed on the outermost surface in a radial direction of stator cores of the resolver, a mounting hole is formed on the flange portion, and the resolver is fixed to the housing by a bolt through the mounting hole.
FIG. 8 shows a cross sectional view of a motor with the resolver shown in Japanese Unexamined Patent Application Laid-open No. 2006-242758. A motor 60 is mounted to a motor housing 63, as shown in FIG. 8. A rotor 68 of a resolver 62 is mounted on an output shaft 61 of the motor 60, and a stator 70 of the resolver 62 is arranged at an outer side of the rotor 68 and is mounted in a motor housing 63 by bolts 69. The stator 70 has a structure in which a plurality of plates formed by punching a magnetic steel sheet in a predetermined shape, etc., is laminated in an axial direction. An end plate 71 arranged at the outermost side of a plurality of plates that constitute the stator 70 has a different shape from those of other plates 72. The end plate 71 has flanges 71c protruding outwardly in a radial direction, as shown in FIG. 9, and mounting holes 71d are formed on each flange 71c, respectively. Then, the stator 70 is fixed to the motor housing 63 by bolts 69 through the mounting holes 71d. 
However, the mounting structure of the resolver described in Japanese Unexamined Patent Application Laid-open No. 2013-99000, has a structure in which the stator of the resolver is received in the opening of the fixing member and is fixed in the housing by the fixing member. Therefore, in the case in which machining accuracy of the fixing member is low, there is a problem in that concentricity of the rotor and the stator shifts. When the concentricity of the rotor and the stator shifts, deviation occurs in the air gap between the rotor and the stator that is set to be a predetermined value, and reliability in rotation angle of motor detected based on an output corresponding to the air gap is decreased.
In addition, in the mounting structure of the resolver described in Japanese Unexamined Patent Application Laid-open No. 2006-242758, an end plate 71 arranged at the outermost side of a plurality of plates that constitute the stator 70 has a different shape from those of other plates 72. Therefore, in the case in which a mounting position of the housing for mounting the stator of the resolver disagrees, it is necessary to prepare each end plate that corresponds to the shapes or dimensions thereof, and therefore, the parts cost is increased. Additionally, plates for forming the stator 70 are generally laminated by caulking. However, when plates using two kinds of metals are punched and laminated, work efficiency is deteriorated. Furthermore, in the case in which the mounting position of the housing for mounting the stator of the resolver is different, even if the standard resolver can be used, it is necessary to prepare each end plate that corresponds to the shapes or dimensions thereof, and therefore, the parts cost is increased.
In view of such circumstances, it is an object of the present invention to provide a structure for mounting a resolver in a housing, in which it is not necessary to use various different plates for forming the stator and the accuracy of concentricity of the rotor and the stator is prevented from decreasing by a simple structure.